1. Field of the Invention
The present invention relates to a device having several contact areas and to a contacting method and, in particular, to an aligning-free contacting method for devices having two terminals.
2. Description of the Related Art
Electronical devices are employed to an increasing extent in both everyday and special applications. In manufacturing, the electronical devices and/or semiconductor devices which are usually referred to as chips have to be connected to a substrate. Instead of a connection of chip and substrate, chip and chip, chip and wafer or substrate and substrate may also be connected.
Many low current consumption semiconductor devices comprise a two-terminal arrangement. Apart from diodes, typical examples include integrated circuits (ICs) of contactless chip cards or, more specifically, so-called smart labels. This term refers to thin ICs having an approximate shape of a cube, embedded in thin substrates, which is a segment on the market growing particularly fast. However, for labelling everyday products, like, for example, in supermarkets, smart labels should become much cheaper in the future. Expenses may potentially be saved in all fields of label production and the cost of chip mounting may be reduced considerably over the next few years.
Typically, pads or contact areas by means of which an integrated circuit is frequently contacted, are mostly arranged in edge regions on one side (active side) of the chip. For contacting by means of standard methods, this means that either the active side faces an upward direction, i.e. away from the carrier substrate, or a downward direction towards the carrier substrate. In the first case, the device is frequently mounted by means of glue and subsequent wire contacting. In the second case, a so-called flip-chip technique is employed. Here, the chip, with its active side and its contact areas facing down, is soldered or glued to corresponding contact areas of the substrate. In order to ensure secure contact, the contact areas are provided with metallic bumps on one side or both sides.
When mounting by means of glue, the glue is generally cured using pressure. DE 102004014214, however, describes a method using a glue having special conductive particles, such as, for example, silver (Ag), such that pressure only has to applied once for a short time before curing in order to compress the conductive particles.
Recently, developments towards reducing requirements regarding an aligning precision and/or using self-aligning processes can frequently be found in small devices. Methods operating in accordance with the key-hole-principle are applied in the latter case. Examples of this are trapezoid-shaped recesses in an accomodation substrate into which correspondingly shaped chips are washed for example using a liquid. Such a method is, for example, described in the published application DE 10105872 A1 or in “Fluidic Self Assembly as Applied to RFID”, Glenn Gengel of Alien Technologies in Low-Cost RFID IC Packaging and Assembly, Workshop, organized by Tech Search and Fraunhofer IZM, Nov. 14, 2005.
The contacting process still necessary is to be seen as a considerable disadvantage of this self-aligning methods.
In order to reduce requirements to aligning precision, an arrangement of the contacts on the lateral faces and/or along one or several edges of a chip is employed. Examples of this are described in DE 10321214 A1, JP 61077352 A or U.S. Pat. No. 5,126,286. In these methods, contacts and/or contact areas of the chip still need to be aligned with respective terminal pads of the substrate.
From the manufacturing point of view, these contacting methods still entail high complexity and, thus, great expenses.